Machine for milling knurls.



F. MULLER.

MACHINE FOR MILLING KNURLS.

APPLICATION FILED MAY 9. 1917- Patented Dec. 17, 1918.

5 SHEETS-SHEET lanue'wtoz F a z M 2g 54 J. ffzzzev F.-MULLER.

MACHINE FOR MILLING KNURLS.

APPLICATION FILED MAY 9. 1911.

Patented Dec. 17, 1918.

5 SHEETS-SHEET 2- ill Hill Ltozneq F. MULLER. MACHINE FOR MILLING'KNURLS.

APPLICATION FILED MAY 9. 1917.

Patented "Dec. 17, 1918.

5 SHEETS-SHEET 3- F. MULLER MACHINE FOR MILLING KNURLS.

APPLICATION FILED MAY 9. 1917.

F. MULLER.

MACHINE FOR MILLING KNURLS.

APPLICATION FILED MAY 9. I917.

Patented Dec. 17, 1918.

5 SHEETS-SHEET 5.

Svwewfoz F M. B4 I UNITED STATES PATENT OFFICE.

FRIEDERICH MULLER, OF HARTFORD, CONNECTICUT, ASSIGNOR TO PRATT & WHITNEY COMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW JERSEY.

MACHINE FOR MILLING KNURLS.

Specification of Letters Patent.

' Patented Dec. 17, 1918.

Application filed May 9, 1917. Serial No. 167,896.

To ((72 whom it may concern Be it known that I, Fnmnnnron MI'JLLER, a citizen of the United States, residing at Hartford, in the county of Hartford and State of Connecticut, have invented certain new and useful Improvements in Machines forl\'lilling Knurls, of which the following is a specification.

The invention relates to a milling machine primarily intended and adapted for the cutting of spiral grooves in cylindrical blanks to form knurls. It will be understood. however, that while the machine is especially adapted for forming knurls, it may by suitable modifications, be adapted for other uses, and it will further be understood that several of the parts of the machine may be used separately from other parts and may be embodied in machines quite diflerent in construction and operation.

()ne of the objects of the invention is to provide a knurl milling or equivalent machine having two or more spindles upon which knurl blanks may be carried to be simultaneously milled. Another object of the invention is to provide improved means wherebv all of the spindles may be simultaneously and uniformly indexed. A further object of the invention is to provide improved means whereby the knurl blanks and the milling cutters are separated fro each other on the return movement.

Another object of the invention is to provide improved means whereby right or left spiral grooves may be formed as required. Another object of the invention is to provide means for stopping the operation of the machine after a blank has been completely milled. Still another object of the invention is to provide an improved indexing mechanism. Additional objects of the invention will be apparent from the following specification and claims.

In the accompanying drawings I have shown the embodiment of the invention which I now deem preferable, but it will be understood that the invention can be embodied in other ways and that the drawings are intended to be merely illustrative and are not intended to define or limit the scope of the invention, the accompanying claimsbeing relied upon for that purpose.

Of the drawings:

Figure 1 is a plan view, certain of the parts being shown in section along the line 11 of Fig. 2.

Fig. 2 is a front elevation. In this view also the mechanism which carries the blanks to be milled is shown in abnormal intermediate position for the sake of convenience of illustration.

Fig. 4 is a fragmentary vertical sectional view taken along the line 44 of Fig. 3, the parts of the machine being shown in the same relative positions as in Figs. 2 and 3.

Fig. 5 is av diagrammatic view showing a development of the cam for moving the mandrel carrying carriage.

Fig. 6 is a perspective view showing the cam for turning the mandrel carrying spindles.

Fig. 7 is a fragmentary view showing the indexing mechanism in a positiondiflerent from that shown in Fig. 2.

Fig. 8 is a fragmentary view showing the indexing mechanism adjusted for operation in the opposite direction.

Referring to the drawings, 1 is a base or bed upon which the other parts of the machine are mounted. Extending upward from the bed 1 is a housing 2 and mounted in suitable bearings in the housing are one or more cutter spindles. Preferably I provide three spindles 3, 4 and 5 as shown, but it will be understood that the number may be varied without departing from the spirit of the invention. In fact, so .far as certain features of the invention are concerned, a single spindle may be provided. Each spindle is arranged horizontally, and when there is a plurality of spindles they are arranged in parallelism in the same vertical plane and are preferably equally spaced. Mounted on the spindles are. milling cutters 6 of suitable form, and for milling knurls these are usually simply V-shaped cutters. The several cutters are arranged with their cutting points all in the same vertical plane.

Suitable means are provided for driving all of the cutter spindles in unison, and as shown, all of the spindles are driven from a common drive shaft 7 provided with a belt wheel 7. The shaft 7 carries a gear wheel 8 which meshes with gear wheels 9 and 10 mounted respectively on the upper two spindles 3 and 4. There is also provided an idler gear 11 which meshes withthe gear 10 on theintermediate spindle 4 and also with a similar gear 12 on the, lower spindle 5. By means of this gearing all of the spindles are rotated continuously in the same direction.

Carried by the lower part'of the base 1 is a frame 13 which carries the devices for holding and for moving and adjusting the blanks to be milled. Supported on the frame 13 is a carriage 14 which is horizontally movable along lines which are normally at an obtuse angle to the axes of the spindles 3, 4 and 5 as shown in Fig. 1. Longitudinally arranged on the carriage 14 are one or more horizontal work carrying spindles, the number of spindles being the same as the number of the cutter carrying spindles. These spindles are shown atl5, 16 and 17 and are positioned in the same vertical plane, being equally spaced. Each spindle is formed with a socket adapted to receive and impart rotative motion .to a mandrel 18. The several mandrels 18 are of such size and shape -as to be adapted to receive and hold the blanks to be milled. As shown, each mandrel is provided with a nut 19 for locking the blanksin place. In practice, when knurls are being milled, two blanks are mounted on one mandrel.

Preferably supplemental bearings are pro vided at the ends of the mandrels, these bearings being in the form of bushings 2O mounted in a bracket 21 which is supported on the frame 13 independently of the carriage 14. Preferably the bushings 20 are longitudinally adjustable so as to give the maximum amount of support to the mandrels under varying circumstances. As shown, there is provided a set screw 22 in connection with each bushing for looking it in adjusted position.

For moving the carriage 14 and the spindles and mandrels carried thereby with respect to the cutters 6, I provide a rotatable cam drum 23 which is engaged by a roller 24 depending from the carriage. The drum 23 is secured to a horizontal shaft'25 which is mounted in bearings in the frame 13. Formed in the periphery of the drum 23 is a cam groove in which the roller 21 is positioned. A development of the druin 23 is shown in Fig. 5.

For turning the shaft 25 and the cam drum thereon there is provided a worm wheel 26 which is secured to the shaft and which meshes with a worm 27 secured to a vertical shaft 28. The vertical shaft 28 carries a bevel gear 29 which, meshes with a bevel gear 30 on a horizontal shaft 31. This shaft 31 is mounted in bearings on the housing 2 and is driven fromthe main drive shaft 7 by means of a belt-32 passing over. pulleys 33 and 34. It will be seen that by means of the mechanism described, power will be transmitted from the main drive shaft 7 to rotate the shaft 25 and/the drum 23. As the drum rotates the roller 24 engaging the sides of the cam groove will cause the carriage 14 and the parts mounted thereon to slowly reciprocate. The groove is so formed that the movement of the carriage in the forward direction (that is toward the cutters) wilL be quite slow, whereas the return movement. away from the cutters will be much faster. It will be understood that milling of the blanks is effected during the slow forward movement of the carriage and that no milling takes place during the more rapid backward movement. 7

Preferably as shown at 35 in Fig. 5, the cam drum 23 is provided with a supplemental groove which permits the carriage '14 to be moved backward to an abnormal been removed and other blanks have been put in place, the carriage can be again moved forward into position for normal reciprocation. Preferably, in order to conveniently 10.5 effect this abnormal backward movement of the carriage, there is provided a rack 36 on the carriage which is engaged by a pinion 37 on a short horizontalshaft which carries a hand wheel 38, and by turning the hand wheel the carriage can be moved backward and forward in the way described.

Means are provided for effecting relative movement vertically between the cutter carrying spindles 3. 4 and 5 and the work carrying spindles 15, 16 and 17. In this way the machine can be adjusted to accommodate blanks of different diameters or to vary the depths of the grooves which are cut. Preferably this adjustment is effected bymoring 1120 the cutter carrying spindles,and in order that this may be done, the spindles instead of being mounted directly on the housing 2 are carried by a slide 39 whichis vertically movable on the housing. This slide is under the control of a screw 40 and by means of this screw the slide may be raised or lowered as required. For locking the slide in adjusted position there is provided a beveled gib -11 which can be clamped between the slide and the housing by means of screws 42.

As already stated, milling is effected during each forward movement of the carriage, and in order that the cutters may not mar or additionally cut the blanks dur ng the return movement of the carriage, I provide means whereby the blanks and the cutters K are separated during the return movement of the carriage. Preferably the carriage is lowered, thus holding the blanks away from the cutters. As shown in the drawings, the carriage 14 is not carried directly by the frame 13 but on an intermediate apron plate 43 which at one side is pivotally connected to the frame 13 by means of pivot pins 44, 44. Interposed between the other side of the plate 43 and the bottom part of the frame 13 is a pair of toggle links 45 and 46. The u per link is pivoted to the apron plate at 47 the bottom link is pivoted to the frame at 48 and the two links are pivoted together at 49. When the links are in alinement with each other, as shown in Fig. '2, the plate 43 is in its upper position and the blanks are held in position to be milled. When the toggle is broken as shown in Fig. 4 the plate 43 is swung downward about the axes of the pivot pins 44, 44 and the blanks are removed from operative relationshi with the cutters. For moving the toggle links to effect the above described movement of the plate 43 and of the blanks, I provide a-cam 'disk 50 secured to the shaft 25. This disk is provided with a cam groove in which is positioned a roller 51 carried by the pivot pin which connectes the two toggle links at 49. The cam groove in the disk 50 1s so shaped and positioned with respect to the cam drum 23 that the links 45 and 46 are held in alinement during the normal movement of the carriage and are then moved out of alinement to lower the blanks during the return movement of the carriage.

Preferably, in order to limit the upward movement of the .plate 43 and to hold the plate absolutely rigid during cutting, I provide two vertical stop rods 52, 52 ,which are threaded into the bottom part of the frame 13 and which are provided with heads which are positioned in recesses in the plate 43.

Preferably these recesses are covered by disks 53, 53.

As shown in Fig. 3 the pivot pin at 48 has bearings at both sides of the link 46. The central part of the pin which is engaged by the link is eccentric. It will be clear that by turning the pin the link may be raised or lowered, thus making it possible .to so adjust the toggle that it will press the plate 43 firmly up against the heads on the rods 52. The pin 48 may be turned by means of the squared end at 54 and may be locked 1n adjusted position by means of the set screw 55.

In order that spiral grooves may be cut 1n the blanks, means are provided for turning the spindles 15, 16 and 17 as the carriage advances. To rovide forthe turning of all of the spind es simultaneously and .to the same extent, they are connected together by suitable gearing. As shown in Fig. 3, the spindles are provided respectively with gear wheels .56, 57 and 58. As shown by dotted lines in Fi 4, the two gear wheels 56 and 5.7 mesh with an idler gear 59 and the two gear wheels 57 and 58 mesh with an idler gear 60. In this way all three of the spindles are connected for simultaneous and uniform movement. For turning the spindles one of them (preferably the middle spindle 16) is mounted in a sleeve 61 .which is provided with a spiral groove 62 (see Fig. 6). The angle of the groove 62 is the same as the angle which the grooves to be cut in the blank are to have. The body part of the carriage 14 adjacent the sleeve 61 is provided with a longitudinal slot 63, and projecting'upward from the plate 43 adjacent the slot 63 and the groove 62 is a bracket 64. This bracket carries a pin 65 which extends into the slot 63 and which carries at its end a roller 66 positioned in the groove 62. It will be seen that as the-carriage 14 is moved longitudinally carrying with it the sleeve 61, the roller 66, by virtue of its engagement with the sides of the roove 62, will cause the sleeve 61 to turn. he sleeve carries .with it the spindle 16 which, through.

, that when the carriage is moved backward the spindles are held against turning.

A suitable indexing mechanism is provided for causing a series of evenly spaced grooves to be cut in the blanks, and preferably this indexing mechanism is constructed to work automatically. As shown in Figs. 1, 2, 3 and 6, two disks 68 and 69 are secured to the rear end of the spindle 16. The sleeve 61 is rovided at its rear end with a flange 70 Wlllcll lies closely adjacent the disk 68. The disk is provided with a series of notches 71, there being as many notches as it is desired to have grooves in the finished blanks. As shown most clearly in Fig. 3, there is provided a plunger 72 which is mounted in a radial aperture in the flange 70. This plunger is normally pressed inward by means of a coil spring. Projecting from one side of the flange is a tooth 73 .which is adapted to engage one or another of the notches 71 in the disk 68, thus locking the disk and the flange together and in this way positively connecting the sleeve 61 with the spindles 16, 15 and 17.

The body part of the carriage is provided with a T-slot 7-1 which is in the form. of a circular arc concentric with the spindle 16. Adjustably held in place by means of a bolt engaging the slot 7-1 is a block on which is pivotally mounted a latch 76 having a cam projection 77. A spring normally holds the latch in the position shown in Fig. 2, but the latch can swing when necessary in the counter-clockwise direction against the pressure of the spring. The plunger 72 is provided with a pin 78 which is adapted to engage the cam projection 77 of the latch 76.

At the beginning of the forward movement of the carriage the pin 7 8 occupies a position at the left of the cam projection 77, assuming that right-hand grooves are to be cut. As the carriage moves forward the pin moves toward the right moving under the projection 77, the spring yielding to permit such movement. However, when the carriage is moved backward the pin 71 will be moved toward the left and .will engage the cam projection 77 and will be forced up the inclined surface thereof. As the pin is forced upward it moves the plunger 72 outward and disengages the tooth 73 from its notch in the disk 68, thus momentarily disconnecting the disk from the flange 70.

Rotatably mounted for movement about the axis of the spindle 16 is an arm 79. This arm is bifurcated, the two parts thereof having bearings at opposite sides of the disk 69. Mounted in the arm 79 is a radially movable plunger pressed inward by a coil spring. The plunger is provided With a beveled tooth 80 adapted to engage ratchet teeth formed on the periphery of the disk 69. The spring is of suflicient strength to normally hold the tooth in engagement with the disk without relative movement.

Formed in the body part of the carriage at opposite sides of the center thereof, are two T-slots 81 and 82 each in the are of a circle and concentric with the spindle 16. Held in place by means of a bolt engaging theT-slot 81, is a block 83: Slidably mounted in this block is a plunger 84 which is inclined as shown and which is normally pressed downward by means of a coil spring. Held in place by a bolt engaging the T-slot 82 is a block 85. Slidably mounted in this 'block is a plunger 86 which is inclined as ShOWn and which is normally pressed downward by means of a coil spring. The two plungers 84 and 86 are similar to each. other and are similarly mounted except that they are oppositely inclined. The-block 83 is so adjusted that the plunger 84 is held in position to engage the arm 79 near the end of the forward movement of the carriage, that is, near the end of the clockwise movement of the spindle 16 and the associated parts. This engagement of the arm 79 with the plunger 84 causes the tooth 80 to slip relatively backward over one or more teeth of the disk 69. Near the end of the subsequent backward movement of the carriage and the corresponding movement of the spindle 16 and the associated parts in the counter-clockwise direction, the arm 79 is carried into engagement with the plunger 86 which is properly adjusted in position. This engagement of the arm 79 with the plunger 86 prevents the continued movement of the disk 69 and of the disk 68 which is connected therewith. The parts are So adjusted relatively that this engagement of the arm 79 with the plunger 86 takes place at the instant when the tooth 73 is disengaged from the disk 68 in the manner already set forth. The result is that the flange 70, together with the tooth 73, continues to move while the disk is held stationary. This additional movement of the flange 68 and of the tooth is sufiicient to bring the tooth 0pposite the next notch 71 of the disk, into which notch the tooth moves when disengaged by the cam projection 77. In this way the disk 68 and also the spindle 16 and the other spindles 15 and 17, are moved through an angle corresponding to the distance between two of the teeth 71, thus positioning the blanks for the cutting of another set of grooves therein. The operation which has been described takes place repeatedly, the blanks being turned repeatedly through the same small angle until a complete revolution has been made.

Ordinarily for milling knurls it is necessary to provide one or another of three standard pitches. I therefore provide three sets of disks 68 and 69, these being similar to each other except for the numbers of teeth.

Preferably means are provided for automatically stopping the machine after the spindles have been indexed through a complete revolution. The mechanism shown comprises an arm 87 'Which is frictionally held on the end of the spindle 16. This arm has a central longitudinal flange 88. There i also a lever 89 pivotally mounted at 90. The lever 89 carries a pin 91 which projects through an aperture in a block 92. Engaged by the end of the pin 91 is a ring 93 connected to the lower end of a chain or cord 94. This chain'or cord extends to a suitable device for interrupting the power. This device is not shown as it constitutes no part of the invention, but for convenience it may be assumed to be a weight or springoperated belt shifter. During-normal operation of the machine the ring is engaged by the pin, as shown, and power is continuously applied to the belt wheel 7 on the drive shaft 7. When the operation zontal alinement with tile point of the lever 89 with the result that upon 'thenext backward movement of the carriage the arm and the lever engage. The arm is swung, thus withdrawing the pin 91 int the block 92 and disengaging it from the ring 93. The chain or cord 94 is now free to move upward, thus interrupting the transmission of power.

The operator now moves the carriage backward still farther by means of the hand wheel 38in the way already described. The milled knurls are then removed from the mandrels and new blanks put in place.

- Then the carriage is returned to normal position and the machine is started by pulling downward on the cord or chain 94 and engaging the ring 93 with the pin 91.

For the milling of knurls it is necessary to provide not only for the cutting of righthand spiral grooves but also for the cutting of left-hand spiral grooves. In fact, knurls are usually supplied in pairs, one left-hand and one right-hand. A machine embodying my invention is adapted for forming grooves of either sort. Up to the present point I have referred solely to the cutting of right-hand spiral grooves, and I will now describe the manner of cutting left-hand spiral grooves.

The frame 13 is not fixedly connected with the base 1 but is movable thereonabout a vertical axis which is coincident with the axis of the shaft 28, this shaft in fact serving as a pivot pin. Bolts 95, 95 are provided for locking the frame 13 and the base 1 together, the base 1 being provided with two sets of holes, thus permitting the frame 14 to be locked either in the position shown in full lines in Fig, 1 or in the position indi cated by dotted lines in Fig. 1. The full line position is used for cuttingright-hand spirals and the dotted line position for cutting left-hand spirals. It will be seen that inasmuch as the frame 13 is movable about the axis of the shaft 28, the power connec tion with the shaft 31 is maintained notwithstanding the movement of the frame.

For cutting left-hand spirals it is necessary to turn the spindles 15, 16 and 17 in the direction opposite to that before described. In order to provide for such opposite turning the sleeve 61 is preferably provided with a second groove 96 which is similar to the groove 62 except that it is oppositely inclined. There is also a g o e 97 which joins the oove 96 and is similar to the groove 67. y unscrewing the bolt 65 the roller 66 may be removed from the groove 62 and then the sleeve 61 may be turned to permit the roller to enter the groove 96.

For indexin the disk 69 and the-arm 79 are removed from the spindle 16 and reversed as shown in Fig. 7. Held in place by a bolt engaging the aforesaid T-slot 74 is a block 98 carrylng a spring-pressed latch 99 having a cam. projection 100, these parts being similar respectively to the parts 75, 76 and 77 except that they are oppositely formed. In operation, the pin 78, at or near the beginning of the forward movement of the carriage, moves counter-clockwise past the cam pro ection 100 causing the latch 99 to swing against the action of the spring.

'Near the end of the forward movement of the carriage the arm 79 engages the plunger 86, thus causing the tooth 80 to slip over one or more teeth on the disk 69. Near the end of the backward movement of the carriage the arm 79 engages the plunger 84', thus stopping the turning movement of the disks 68 and 69. At substantially the same time the pin 78 is forced upward along the inclined surface of the cam projection 100, thus disengaging the tooth 73 from its notch in the disk 68. The flange with the tooth 73 continues to move and when the pin 78 has passed the cam projection 100 it drops into the next notch of the disk 68, thus indexing the spindles through an angle corresponding to the distance between two notches.

What'I claim is:

1. The combination in a millin machine of a plurality of parallel blan -carrying spindles, a plurality of rotatable milling cutters adapted respectively to engage blanks carried by the spindles and having their cutting planes coincident and at an angle to the plane of the spindle axes, and means for relatively moving the spindles in unison longitudinally and for. simultaneously turning them to effect the milling of spiral grooves in the blanks.

2. The combination in a milling machine of a plurality of parallel blank-carrying spindles, a plurality of rotatable milling cutters adapted respectively to engage blanks carried by the spindles and having their cutting planes coincident and at an angle to the plane of the spindle axes, means for relatively moving the spindles in uni son longitudinally and for simultaneously turning them to effect the milling of spiral grooves in the blanks, and means for moving the cutters in unison toward or from the axes of the spindles to change the depth of the grooves;

3. The combination in a milling machine of a plurality of parallel blank-carrying spindles, a plurality of milling cutters rotatable about parallel axes and adapted respectively to engage blanks carriedby the spindles, means for relatively moving the spindles in unison longitudinally, means for connecting the spindles together for simultaneous rotative movement, an element carried by one of the spindles and having a spiral cam groove, and a roller projecting into the groove and fixed against longitudinal movement whereby the spindles are turned durin longitudinal movement.

4. The com ination in a milling machine of a plurality of parallel spindles, blankholding mandrels carried respectively by the spindles, a plurality of milling cutters rotatable about parallel axes and adapted respectively to engage blanks on the mandrels, means for longitudinally reciprocating the spindles and mandrels, and bearings for supporting the ends of the mandrels, the said bearings being normally non-reciprocatory but manually adjustable longitudinally.

5. The combination in a milling machine of a plurality of parallel spindles, blankholding mandrels carried respectively by the spindles, a plurality of milling cutters ro-' tatable about parallel axes and adapted respectively to engage blanks on the mandrels, means for longitudinally reciprocating the spindles and mandrels, non-reciprocatory bearings for supporting the ends of the mandrels, and manually controllable means for moving the spindles and mandrels abnormally to withdraw the mandrels from the bearings to permit the unloading and loading of the mandrels.

6. The combination in a milling machine of a spindle, a blank-holding mandrel carried by the spindle, a rotatable milling cutter adapted to engage a blank on the mandrel, a non-reciprocatory bearing for supporting one end of the mandrel, a drum rotatable about an axis parallel to the spindle and having a cam groove, and a roller connected with the spindle and extending into the groove whereby the spindle is reciprocated as the drum is turned, the drum also having a supplemental longitudinal groove permitting an abnormal backward movement of the spindle to withdraw the mandrel from the non-reciprocatory bearmg.

7 The combination in a milling machine of a spindle, a blank-holding mandrel carried by the spindle, a rotatable milling cutter adapted to engage a blank on the mandrel, a non-reciprocatory bearing for supportlng the end of the mandrel, a drum rotatable about an axis parallel to the spindle and having a cam groove, a roller connected with the spindle and extending into the groove whereby the spindle is reciprocated as the drum is turned, the drum also having normal backward movement of the spindle is permitted. 1

8. The combination in a milling machine of a plurality of parallel blank-carrying spindles, a plurality of milling cutters rotatable about parallel axes and adapted respectively to engage blanks carried by the spindles, means for relatively reciprocating the spindles in unison longitudinally to effect milling, and automatically acting means for separating the spindles and cutters during movement in one direction and for restoring them to normal relationships during movement in the other direction.

9. The combination in a milling machine of a plurality of parallel blank-carrying spindles, a plurality of milling cutters rotatable about parallel axes and adapted respectively to engage blanks carried by the spindles, means for relatively reciprocating the spindles in unison longitudinally to effect milling, means for turning the spindles in synchronism during milling to efiect the cutting of spiral grooves in the blanks, and automatically acting means for separating the spindles and cutters during movement in one direction and for restoring them to normal relationships during movement in the other direction.

10 The combination in a milling machine of a reciprocating table, an apron plate pivoted to the table for movement about an axis parallel to the lines of reciprocation, a rotatable spindle carried by the apron plate parallel to the axis of the pivot thereof, a rotatable milling cutter adapted to engage a blank carried by the spindle, and means for holding the apron plate in a normal upper position with the blank engaged by the cutter during movement of the table in one direction and for moving it about its pivot to a lower retracted position during movement of the table in the other directlon.

11. The combintaion in a milling machine of a reciprocating table, an apron plate connected to the table for movement upward and downward, a rotatable spindle carried by the apron plate parallel to the lines of reciprocation of the table, a rotatable milling cutter adapted to engage a blank carried by the spindle, and a pair of toggle links for holding the apron plate in a normal upper position with the blank enin synchronism optionally in either direcgaged by the cutter durin movement of the table in one direction an for moving it to a lower retracted position during movement of the table inthe other direction.

12. The combination. in a milling machine of a reciprocating table, an apron plate connected to the table for movement up-' ward and downward,- a rotatable spindle carried by the apron plate parallel to the lines of reciprocation of the table, a rotatable milling cutter adapted to engage a blank carried by the spindle, a pair of toggle links for holding the apron plate in a normal upper position with the blank engaged by the cutter during movement of the table in one direction and for moving it to a lower retracted position during movement of the table in the other direction, a roller carried by the toggle links at the joint between them, and a cam member engaging the roller to operate the links.

13. The combination in a milling machine of a reciprocating table, an apron plate connected to the table for movement upward and downward, a rotatable spindle carried by the apron plate parallel to the lines of reciprocation .of the table, a rotatable milling cutter adapted to engage a blank carried by the spindle, a stop for limiting upward movement of the apron plate, and toggle links for holding the apron plate in a normal upper position in engagement with the stop during movement of the table in one direction, and for moving it to a lower' retracted position during movement of the table in the other direction.

14;. Thecombination in a milling machine of a reciprocating table, an apron plate connected to the table for movement upward and downward, a rotatable spindle carried by the apron plate parallel to the lines of reciprocation of the table, a rotatable milling cutter adapted to engage a blank carried by the spindle, a stop for limiting upward movement of the apron plate, and toggle links for holding the apron plate in a normal upper position in engagement with the stop during movement of the table in one direction and for moving it to a lower retracted position during movement of the table in the other direction, and means for adjusting one of the pivots for the links.

15. The combination in a milling machine of a plurality of parallel blank-carrying spindles, a plurality of milling cutters rota table about parallel axes and adapted respectively to engage blanks carried by the spindles, means for relatively reciprocating the spindles in unison longitudinally to effeft milling, and means for turning the spindles tion durin milling to effect the cutting of right or le t spiral grooves in the blanks.

16. The com ination in a milling machine of a plurality of parallel blank-carrying spindles, a plurality of milling cutters rotatable about parallel axes and adapted respectively to engage blanks carried by the spin-" dles, means for relatively reciprocating the during milling to effect the cutting of right or left spiral grooves in the blanks, and means for relatively adjusting the spindles and the cutters angularly to conform to the pitch angle of the spirals.

17. The combination in a milling machine of a plurality of parallel blank-carrying spindles, a plurality of rotatable milling cut ters adapted respectively to engage blanks carried by the spindles and having their cutting planes coincident and at an angle to the lane of the spindle axes, means whereby t e spindles may be adjusted angularly, means for relatively moving the spindles in unison longitudinally and for simultaneously turning them to effect the milling of spiral grooves in the blanks, and means for changing the turning movement of the spindles whereby the pitch angle of the spirals may be the same as the angle of the cutting planes of the cutters.

18. The combination in a milling machine of a blank-carrying spindle, a rotatable milling cutter adapted to engage a blank carried by the spindle, means'for relatively moving the spindle longitudinally, an element carried by one of the spindles having two oppositely formed spiral cam grooves, and a roller adapted to project into either of the grooves and fixed against longitudinal movement whereby the spindle may be turned in either direction during longitudinal movemen 19. The combination in a milling machine of a plurality of parallel blank-carrying spindles, a plurality of milling cutters rotatable about parallel axes and adapted respectively to engage blanks carried by the spindles, means for relatively moving the spindles in unison longitudinally, means for con necting the spindles for simultaneous rotative movement, an element carried by one of the spindles having two oppositely formed spiral cam grooves, and a roller adapted to project into either of the grooves and fixed against longitudinal movement whereby the spindles may be turned in either direction during longitudinal movement.

20. In a milling machine, the combination of a main frame, a plurality of rotatable cutters carried by the main frame and arranged withtheir axes horizontal and in the same vertical plane, a supplemental frame vertically pivoted to the main frame and adapted to be secured in either of two positions, a plurality of spindles carried by the supp'le mental frame and arranged with their axes horizontal and in the same vertical plane,

to be secured in either of two positions, a plurality of spindles carried by the supple-- mental frame and arranged with their axes horizontal and in the same vertical plane, a rotatable shaft bodily movable with the supplemental frame, a cam on the shaft adapted to longitudinally reciprocate the spindles whereby blanks carried thereby are brought respectively into engagementwith the cutters, and a second cam on the shaft adapted to hold the spindles in normal position during movement in one direction and to lower them during movement in the other direction. 22. The combination in a milling machine i of a plurality of parallel blank-carrying spindles, a plurality of milling cutters rotatable about parallel axes and having their cutting planes coincident, the said cutters being adapted respectively to engage blanks carried by the spindles, means'for relatively moving the spindles in unison longitudinally to effect milling, and means for indexing the spindles simultaneously through equal angles.

23. The combination in a milling machine of a plurality of parallel blank-carrying spindles, a plurality of milling cutters rotatable about parallel axes and adapted respectively to engage blanks carried by the spindles, means for relatively reciprocating the spindles in unison longitudinally to effect milling, and means for automatically indexing the spindles simultaneously through equal angles after each milling operation.

24. The combination in a milling machine of a plurality of parallel blank-carrying spindles, a plurality of milling cutters rotatable about parallel axes and adapted respectively to engage blanks carried by the spindles, means for relatively reciprocating the spindles in unison longitudinally to effect milling, means for automatically indexing the spindles simultaneously through equal angles after each milling operation, and means for automatically stopping the machine after the spindles have been indexedtLrough a complete revolution.

25. The combination in a milling machine of a parallel blank-carrying spindle, a rotatable milling cutter adapted to engage a blank carried by the spindle, means for relatively reciprocating the spindle longitudinally to effect milling, means for turning the spindle optionally in either direction during milling to effect the cutting of right or left spiral grooves in the blank, and means for indexing the spindle optionally in either direction simultaneously through equal angles. a

26. The combination in a milling machine of a plurality of parallel blank-carrying spindles, a plurality of milling cutters rotatable about parallel axes and adapted respectively to engage blanks carried by the spindles, means for relatively reciprocating the spindles in unison longitudinally to effect milling, means for turning the spindles in synchronism optionally in either direction during milling to effect the cutting of right or left spiral grooves in the blanks, and means for indexing the spindles optionally in either direction simultaneously through equal angles.

27. The combination in a'milling machine of a blank-carrying spindle, a rotatable milling cutter adapted to engage a blank carried by the spindle, means for relativelyreciprocating the spindle longitudinally to effect milling, means for turning the spindle optionally in either direction during milling to effect the cutting of right or left spiral grooves in the blank, means for indexing the spindle optionally in either direction simultaneously through equal angles, and means for stopping the machine after the spindle has been indexed through a complete revolution.

28. In a milling machine, the combination of a rotatable spindle, -a rotatable milling cutter adapted to engage a blank carried by the spindle, means for longitudinally reciprocating the spindle, a sleeve mounted concentrically with the spindle and movable longitudinally therewith, means dependent upon longitudinal movement of the sleeve for rotating it, means normally connecting the sleeve and spindle for synchronous rotative movement, and means for momentar1ly disconnecting the sleeve and spindle,

it is disconnected from the sleeve, whereby relative movement of the sleeve takes place to effect indexing.

30. In a milling machine, the combination ofa rotatable spindle, a rotatable milling cutter adapted to engage a blank carried by the spindle, means for longitudinally reciprocating the spindle, a sleeve mounted concentrically with the spindle and movable longitudinally therewith, means dependent upon longitudinal movement of the sleeve for rotating it, a movable tooth normally connecting the sleeve and spindle for synchronous rotative movement,'and a cam element for momentarily moving the tooth to disconnect the sleeve and spindle at a definite position during each reciprocation to thereby efiect indexing of the spindle.

31. In a milling machine, the combination of a rotatable spindle, a rotatable milling cutter adapted to engage a blank carried by the spindle, means for longitudinally reciprocating the spindle, a sleeve mounted concentrically with the spindle and movable longitudinally therewith, means dependent upon longitudinal movement of the sleeve for rotating it, means normally connecting the sleeve and spindle for synchronous rotative movement, means for momentarily dis connecting the sleeve and spindle at a definite position during each reciprocation of'th'e spindle, an arm connected with the spindle, and a stop adapted to engage the arm to stop the rotation of the spindle when the sleeve and spindle are disconnected, whereby relative movement of the sleeve takes place to effect indexing.

32. In a milling machine, the combination of a rotatable spindle, a rotatable milling cutter adapted to engage a blank carried by the spindle, means for longitudinally reciprocating the spindle, a sleeve mounted concentrically with the spindle andmovable longitudinally therewith, means dependent upon the longitudinal movement of the sleeve for rotating it, means normally connecting the sleeve and spindle for synchronous rotative movement, means for momentarily disconnecting the sleeve and spindle near the end of each backward movement of the spindle, a ratchet wheel connected with the spindle, an arm rotatable about the spindle axis and having a springpressed pawl engaging the ratchet wheel, a stop adapted to engage the arm near the end of the forward movement of the spindle to cause it to carry the pawl relat1vely backward over the teeth 0 the ratchet, and a second sto adapted to engage the arm near the end 0 the backward movement of the spindle to stop the rotation of the spmdle when the sleeve and spindle are dlsconnected, whereby relative movement of the sleeve takes place toefiect mdexmg.

33. In a milling machine, the combination of a rotatabe spindle, a rotatable milling cutter adapted to engage a blank carried by the spindle, means for longitudinally reciprocating the spindle, a sleeve mounted concentrically with the spindle and movable longitudinally therewith, means dependent upon longitudinal movement of the sleeve for rotating it, means normally connecting the sleeve and spindle for synchronous rotative movement, means for momentarily disconnecting the sleeve and spindle at a definite position during each upon longitudinal movement of the sleeve.

for rotating it optionally in either direction, means normally connecting the sleeve and spindle for synchronous rotative movement, and means operable for either direction of spindle rotation for momentarily disconnecting the sleeve and spindle at a definite position during each reciprocation to thereby efl'ect indexing of the spindle.

35. In a milling machine, the combination of a rotatable spindle, a rotatable milling cutter adapted to engage a blank carried by the spindle, means for longitudinally reciprocating the spindle, a sleeve mounted concentrically with the spindle and movable longitudinally therewith, means dependent upon longitudinal movement of the sleeve for rotating it optionally in either direction, means normally connecting the sleeve and spindle for synchronous rotative movement, means operable for either direction 'ofspindle rotation for momentarily disconnecting the sleeve and spindle at a definite position during each reciprocation to thereby efiect indexing of the spindle, and means for stoppin the rotative movement of the spindle w en it is disconnected from the sleeve, whereby relative movement of the sleeve takes place to effect indexing. t

36. Ina milling machine, the combination of a rotatable spindle, a rotatable milling cutter adapted to engage a blank carried by the spindle, means for longitudinally reciprocatin the spindle, a sleeve mounted concentrica ly with the spindle and movable longitudinally therewith, means dependent uponlongitudinal movement of the sleeve during each reciprocation of the spindle to thereby effect indexing of the spindle, one cam element being operable for one direction of rotation and the other for the other direction.

37. In a milling machine, the combination of a rotatable spindle, a rotatable milling cutter adapted to engage a blank carried by the spindle, means for longitudinally reciprocating the spindle, a sleeve mounted concentrically with the spindle and movable longitudinally therewith, means dependent upon longitudinal movement of the sleeve for rotating it optionally in either direction, means normally connecting the sleeve and spindle for synchronous rotative movement, means operable for either direction of rotation for momentarily disconnecting the sleeve and spindle at a definite position during each reciprocation of the spindle, an arm connected with the spindle, and two stops adapted to engage the arm to stop the rotation of the spindle when the sleeve and spindle are disconnected, whereby relative movement of the sleeve takes lace to effect indexing, one stop being operable for one direction of rotation and the other for the other direction.

38. In a milling machine, the combination of a rotatable spindle, a rotatable milling cutter adapted to engage a blank carried by the spindle, means for longitudinally reciprocating the spindle, a sleeve mounted concentrically with the spindle and movable longitudinally therewith, means dependent upon longitudinal movement of the sleeve for rotating it optionally in either direction, means normally connecting the sleeve and spindle for synchronous rotative movement,

means for momentarily disconnecting the sleeve and spindle near the end of each backward movement of the spindle, a ratchet wheel connected with the spindle, an arm rotatable about the spindle axis and havin a spring-pressed pawl engaging the ratcliet wheel, the ratchet wheel and arm being reversible on the spindle in accordance with the direction of rotation, two stops adapted respectively to engage the arm near the end of the forward movement of the spindle to cause it to carry the pawl relatively backward over the teeth of the ratchet and to engage the arm near the end of the backward movement of the spindle to stop the rotation of the spindle when the sleeve and spindle are disconnected, whereby relative movement of the sleeve takes place to eifect indexing, the functions of the said stops being interchanged when the direction of rotation is reversed.

39. In a milling machine, the combination of a rotatable spindle, a rotatable milling cutter adapted to engage a blank carried by the spindle, means for longitudinally reciprocating the spindle, a sleeve mounted concentrically with the spindle and movable longitudinally therewith, means dependent upon longitudinal movement of the sleeve for rotating it optionally in either direction, means normally connecting the sleeve and spindle for synchronous rotative movement, means operable for either direction of spindle rotation for momentarily disconnecting the sleeve and spindle at a definite position during each reciprocation of the spindle to effect indexing, an arm connected with the spindle independently of the sleeve, and means adapted to be engaged bythe arm to stop the operation of the machine when the spindle has been indexed through a complete revolution in either direction.

In testimony whereof, I hereto aflix my signature.

FRIEDERICH MULLER. 

